Method and apparatus for producing, transporting, storing, and/or handling liquid carbon dioxide



2,180,231 METHOD AND- APPARATUS FOR PRODUCING, TRANSPORTING, STORING,

Nov. 14, 1939. E. GEERTZ ET AL AND/0R HANDLING LIQUID CARBON DIOXIDEFiled May 20, 1938 7 SheetsSheet l wwwww mw uwww mwwww. 1 h

' f Sworn M Ef ie 5061i? w fisseif k ylor il WWW Nov. 14, 1939. GEERTZET AL 2,180,231

METHOD AND APPARATUS FOR PRODUCING, TRANSPQRTING, STORING AND/ORHANDLING LIQUID CARBON DIOXIDE Filed May 20, 19-38 7 Sheets-Sheet 2 Nov.14, 1939. I 2,180,231

METHOD AND APPARATUS FOR PFQDUCING, TRANSPORTING, STORING,

E. GEERTZ ET AL AND/OR HANDLING LIQUID CARBON DIOXIDE v 7 Sheets-Sheet 3Filed May 20, 1938 [21k 6081*]? d iliseflikylaz X W MW,

2.180231 STORING,

Nov- 14. 1939. E. GEERTZ ET AL METHOD AND APPARATUS FOR PRODUCING,TRANSPORTING,

AND/OR HANDLING LIQUID CARBON DIOXIDE Filed May 20 1958 7 Sheets-Sheet 43mm if???) 6001i? ""11 E. GEERTZ ET AL 2.18023 TRANSPORTING, STORING,

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Nov. 14, 1939.

METHOD AND APPARATUS FOR PRODUCING,

AND/OR HANDLING LIQUID CARBON DIOXIDE Nov. 14, 1939. E'. GEERTZ ET AL2,180,231 METHOD AND APPARATUS FOR PRODUCING, THANSPORTING, STORXNG,

AND/OR HANDLING LIQUID CARBON DIQXIDE Filed May 20, 1938 7 Sheets-Sheet7 wunmmnm] Patented Nov. 14, 1939 UNITED STATES PATENT OFFICE -EricGeertz, Aurora, and Jesse E. Taylor, Elgin, Ill., assignors to CardoxCorporation Chicago, Ill., a corporation of Illinois Application May 20,1938, Serial No. 209,152

17 Claims.

ment may be utilized and a material reduction in operating expenses maybe brought about.

A further important object of this invention is to provide methods andapparatus for delivering 15 extremely low temperature and correspondinglow pressure liquid carbon dioxide to a transport or stationary storagecontainer; for transferring said liquid carbon dioxide from one type ofstorage container to the other; for preserving or 20 maintaining saidlow temperature and corresponding vapor pressure whilethe liquid carbondioxide is thus stored, and for withdrawing the liquid carbon dioxidefor use when and as desired.

Another object of the invention is to provide 25 apparatus for storingliquid carbon dioxide at a constant low temperature and correspondingvapor pressure indefinitely without loss and at a very low cost.

A still further object of the invention is to pro- 30 vide apparatus forcharging comparatively small containers or cylinders from a storagecontainer of the above mentioned type with a comparatively lowconsumption of power for the charging operation.

35 A further object of the invention is to provide apparatus forhandling liquid carbon dioxide in which maintenance costs resulting fromleakage at joints is virtually eliminated.

Still another object of the invention is to pro- 40 vide methods andapparatus for producing low temperature and corresponding low pressurecarbon dioxide and charging the same into either transport or stationarycontainers.

Another object of the invention is to provide .5 equipment in which thelow temperature and corresponding low pressure carbon dioxide may betransported, stored, and otherwise handled with greater safety thanattended the use of previous high pressure storing and handling {,0equipment.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part 55 of this specification andin which like numerals are employed to designate like parts throughoutthe same,

Figure 1 is a schematic view illustrating one form of method orapparatus embodying this invention for converting carbon dioxide gasinto liquid carbon dioxide having a low temperature and correspondingvapor pressure and charging the said liquid carbon dioxide into either atransport or stationary storage container,

Figure 2 is a similar view to Fig. 1, but illustrates a modified form ofmethod and apparatus for accomplishing the same results,

Figure 3 is a partial side elevational view and partial longitudinalsectional view of a transport type of equipment by means 01' which thelow '15 temperature, low pressure liquid carbon dioxide may be carriedbetween points of storage, or the like, Figure 4 is a vertical sectionalview taken on line 4-4 Of Fig; 3.

Figure 5 is a detail longitudinal or vertical sectional view of thestorage container per se employed in the transportunit disclosed inFigs. 3 and 4,

Figure 6 is a detail longitudinal sectional view of a form of pop-01f orrelief valve which may be employed in connection with the transport unitdisclosed in Figs. 3 and 4,

Figure 7 is a schematic view illustrating a transport container and astationary storage container with mechanism which may be employed fortransferring low temperature, low pressure liquid carbon dioxide fromthe transport container to the stationary storage container,

Figure 8 is a detail sectional view illustrating a cooling coil which isassociated with the stationary storage container disclosed in Fig. 7,

Figure 9 is a schematic view disclosing a storage and charging plantdesigned particularly for use in handling extremely low pressure and lowtemperature liquid carbon dioxide at a distribution point,

' Figure 10 is a schematic view illustrating a modified form ofapparatus for maintaining liquid carbon dioxide stored in a containerrefrigerated to a desired low temperature and corresponding lowpressure,

Figure 11 is a horizontal, longitudinal sectional view of a form ofstorage container structure embodying this invention,

Figure 12 is a longitudinal vertical sectional view of the storagecontainer structure disclosed in Fig. 11,

Figure 13 is a side elevational view of a storage pressure.

container assembly with insulating material applied thereto,

Figure 14 is a top plan view of the assembly shown in Fig. 13,

Figure 15 is a transverse sectional view of the assembly shown in Figs.13 and 14,

Figure 16 is a detail view partly in end elevation and partly invertical section of a reciprocating plunger type of compressor which isemployed as a liquid pump for pumping and compressing low temperature,low pressure liquid carbon dioxide, and

Figure 17 is a longitudinal sectional view of a type of pop-off orrelief valve structure employed for limiting the development ofhydrostatic pressure in a portion of the system disclosed in Fig. 9. I

It has been the practice to commercially handle carbon dioxide duringtransportation and storage as well as when used either in its liquidphase at the varying temperatures of the surrounding atmosphere and thevapor pressures normal to such temperatures or as solid carbon dioxidewhich is usually referred to as dry ice. Liquid carbon dioxide at suchsurrounding atmospheric temperatures will have a vapor pressure usuallyin excess of 1000 pounds per square inch, absolute. If the liquid carbondioxide is confined in a container which is subjected to hot summertemperatures, the vapor pressure may rise as high as 2000 pounds persquare inch, absolute. The equipment which must be employed fortransporting, storing and otherwise handling liquid carbon dioxide atsuch surrounding atmospheric temperatures and the" correspondingexcessive vapor pressures, naturally, is expensive to acquire, installand maintain, and some hazard is involved in confining the material incontainers at indeterminate and fluctuating temperatures.

When carbon dioxide is transported, stored and otherwise handled in itssolid or dry ice state, the rate of loss, due to sublimation, iscomparatively high and it also involves the steps of first convertingthe carbon dioxide to its solid state and then reconverting it to itsliquid or gaseous state, if the carbon dioxide is not to be used in itssolid form.

It has been discovered that material savings in equipment andmaintenance costs may be obtained by transporting, storing, andotherwise handling carbon dioxide in a liquid state when refrigerated tocertain temperatures falling considerably below an atmospherictemperature of 70 F.

One of the principal items of equipment embodying this invention whichresult in a material saving in handling costs are the containers inwhich the unusually low pressure, low temperature liquid carbon dioxideis transported and stored. Containers capable of handling liquid carbondioxide at the high vapor pressures resulting from maintaining theliquid at the surrounding -atmospheric temperatures usually costpurchasers from $450.00 to $600.00 per ton of carbon dioxide capacity,depending upon the capacity of each container and the number ofcontainers purchased at any one time. The present invention contemplatesthe use of insulated containers 'with mechanism capable: of maintainingthe liquid carbon dioxide at the desired low temperature andcorresponding vapor Equipment of this character can be supplied forapproximately $275.00 per ton of carbon dioxide.

Hereinafter the expression sub-atmospheric temperature is usedrepeatedly in the specification and claims. The meaning to be applied tothis expression is based on the frequent use of the expression"atmospheric temperature" as designating 70 F. Sub-atmospherictemperature", therefore, means a temperature below 70 F.

The handling of liquid carbon dioxide, includ ing such operations astransferring the carbon dioxide between different containers, atpressures corresponding to the selected sub-atmospheric temperatures,effects a material saving in the character of pumping equipmentemployed, the power consumed to operate the pumping equipment, jointmaintenance, and the like, when compared to handling this commodity atthe surrounding atmospheric temperatures and their corresponding highvapor pressures. It has been determined .that a power saving ofapproximately may be obtained in the operation of charging plants forsmall cylinders or shells when the liquid carbon dioxide is handled atalow temperature falling within the range of sub-atmospheric temperaturesselected. It also has been determined that the cost of maintainingjoints properly sealed is virtually eliminated.

In considering the entire system of handling and using liquid carbondioxide at the selected sub-atmospheric temperatures and theircorresponding vapor pressures involving this invention, it is found toinvolve first the conversion of carbon dioxide gas at the generatingplant, or at other sources of supply, to the liquid phase and to thedesired sub-atmospheric temperature and its corresponding vapor pressureat which it is to be subsequently handled. Carbon dioxide, of course,may be handled as a liquid at any temperature ranging from approximately87 F. to approximately -70 F. and the vapor pressures which will prevailat these extreme limits will be 1066 pounds per square inch and 75pounds per square inch, respectively. At a temperature of 32 F., thecorresponding vapor pressure is approximately 505 pounds per square inchwhich, when maintained constant, will provide a reasonably satisfactorymaximum working pressure for the type of equipment and methods ofhandling which may be successfully employed in carrying out thisinvention. Oi course, the selection of still lower temperatures willresult in increased economy and safety in the handling and use of liquidcarbon dioxide because such lowered temperatures naturally will beaccompanied by lower vapor pressures. Therefore, probably thetemperatures which will be most frequently selected will fall within themore limited range of from 0 F. to 40 F. which will provide workingpressures for the equipment of from approximately 300 pounds per squareinch to approximately pounds per square inch. It is not difllcult toappreciate the advantages and material savings which will result fromthese appreciable reductions in working pressures.

Secondly, the system involves the storage of the liquid carbon dioxideat the locations where it is produced and at the several points ofdistribution for the system. 01' course, the liquid carbon dioxide mustbe stored and maintained at the selected sub-atmospheric temperature ortemperatures and its corresponding vapor pressures.

Thirdly, the system involves transportation of of the liquid carbondioxide from the plant at which it is produced to the various points 01'distribution while maintaining the said liquid at a desired constantsub-atmospheric temperae ture and its corresponding vapor pressure.

Fourthly, the system involves transferring the low temperature, lowpressure liquid carbon dioxide between the transportation containers andthe stationary storage containers which are located at strategic pointsof distribution relative to the territories being served by the system.This transferring, of course, must be accomplished without rise intemperature and pressure of the liquid carbon dioxide while beinghandled, and

Fifthly, the carbon dioxide usually will be made available for use bybeing placed in small cartridges, cylinders, drums, or the like, inwhich the carbon dioxide will be confined at-the surrounding atmospherictemperatures and the system involves the charging of these smallcontainers from the large capacity storage containers in which thecarbon dioxide is confined at the selected sub-atmospheric temperatureand its corresponding vapor pressure.

In the drawings, wherein for the purpose of illustration are shown thepreferred embodiments of this invention, and referring particularly toFig. 1, there is disclosed the equipment of a plant which is suitablefor use in converting the carbon dioxide gas or vapor, resulting fromstoring the carbon dioxide at atmospheric temperatures, to liquid at aselected sub-atmospheric temperature and its corresponding vaporpressure. The carbon dioxide delivered by the producing plant is fedthrough the pipe 20 into a conventional form of gas holder or receiver2|. This holder or receiver is of conventional construction and needs nofurther explanationf From the gas holder 2|, the carbon dioxide gas isdrawn oil by means of the pipe 22 and is delivered to the low pressureor first stage cylinder 23 of a two stage compressor 24. From this lowpressure or first stage cylinder, the carbon dioxide gas is conducted bythe pipe 25 to the heat exchange zone 26 of the first stage intercoolerwhich is in circuit with the cooling water lines 21. From theintercooler, the lower temperature carbon dioxide gas is conducted bythe pipe 28 to the second stage or high pressure cylinder 29 of the saidtwo stage compressor 24. From the outlet of this second cylinder 29, thehighly compressed carbon dioxide gas is conducted by the pipe 30 to anoil trap 3|. Leading from the said oil trap is a pipe 32 which conductsthe carbon dioxide gas to a second stage cooler through the heatexchange zone 33 of which the carbon dioxide gas passes. This cooler hascirculated therethrough the cooling water by means of the lines 34.

Merely for the purpose of illustrating one set of operating conditionsfor the two stages of compression and cooling, but without intending tolimit the operation of this equipment to any particular values or rangeof values, it will be explained that the first stage of compression,performed by the cylinder 23, may result in delivering the carbondioxide gas at a pressure of 70 pounds per square inch. After beingcooled in the first stage intercooler, forthe purpose of removing theheat absorbed during compressing, the gas is further compressed in thesecond stage cylinder 29 and delivered at a pressure of 300 pounds persquare inch to the second heat exchange unit. From this unit the carbondioxide unit 41 gas may be delivered at a pressure of 300 pounds persquare inch and at 70 F. As stated, these values are given by way ofexample only and may vapor pressure of 280 pounds per square inchthrough the discharge line 31.

To bring about this conversion and cooling of the carbon dioxide, thecondenser 36 is connected in circuit with a suitable commercialrefrigerating system or plant. This plant may include an ammoniacompressor 38 which discharges its ammonia gas through the line 39 to anammonia condenser 40. This ammonia condenser has cooling watercirculated therethrough by means of the pipe lines 4|. The'condensed orliquefied ammonia is discharged from the condenser 40 through the pipe42 into the receiver 43 from which it discharges through the pipe line44 and by the expansion valve 45 to the aforementioned condenser 33. Thereturn line for the ammonia consists of the pipe 46 which extends fromthe condenser 36 back to the ammonia compressor 38.

The low temperature, low pressure liquid carbon dioxide may bedischarged through the condenser outlet pipe 31 directly into atransport if desired. It will be appreciated, however, that thedischarge through the pipe 31 may be into a stationary storage containerif desired, and then transport containers may be charged from thestorage container. After the charging of a transport container 41 withthe low temperature, low pressure liquid carbon dioxide, this containeris moved to any one of the several distribution points where the saidliquid carbon dioxide is delivered to a stationary storage containerfrom which it is eventually drawn oil for use.

In Fig. 2, there is disclosed a plant layout which may be employed forobtaining the low temperature, low pressure liquid carbon dioxide. Thisplant differs from the plant illustrated in Fig. 1 primarily because ofthe substitution of a third stage of compression for the ammoniarefrigerating plant of Fig. 1. The layout or equipment of Fig. 1 ispreferred over that of Fig. 2 because it has been determined that theammonia compressor 33 may be operated at a lower consumption of powerthan that required for the third stage of compression. The equipmentdisclosed in Fig. 2 now will be explained.

A conventional gas holder 48 is provided for receiving the gas from theproducing plant by.

means of the pipe line 49. The carbon dioxide gas is drawn off from theholder 48 through the pipeline 50 and is fed to the first stage ofcompression; i. e., the cylinder 5|, of the three stage compressor 52.From the outlet of this first stage cylinder 5|, the carbon dioxide gasis conducted by the pipe 53 to an oil trap 54 and then to the heatexchange zone 55 of a first stage intercooler by means of the pipe line56. This first stage intercooler is supplied with cooling water by meansof the pipe lines 51. From this cooler, the carbon dioxide gas at, forexample, 10 pounds per square inch, is conducted by the pipe 58 to theintake of the second stage of compression, or the cylinder 53. From theoutlet of this second gas at the said 300 pounds per square inchpressure is led by the pipe 85 to the third stage cylinder 88. From theoutlet for the cylinder 88 of the third stage of compression, the carbondioxide gas at, for example, 1000 pounds per square inch pressure isconducted by the pipe 81 to the heat exchange zone 88 of the third stageaftercooler.

This third stage heat exchange unit is supplied with cooling liquid,such as water, by means of the pipe lines 88.

The gas leaving the third stage aftercooler passes through the pipe line10 to the oil trap II and from this trap-to a drier 12 through a pipeline 18. A condenser 14' receives the carbon dioxide gas from the drier12 as it passes through the pipe line 15. A suitable liquid to effectcondensation of the carbon dioxide gas is fed through the condenser 14by means of the pipe lines 18. The liquid carbon dioxide leaves thecondenser 14 and passes into the liquid carbon dioxide receiver 11 bypassing through the pipe line 18. The liquid carbon dioxide in thereceiver TI is at a pressure of, for example, 1000 pounds per squareinch with a temperature of, for example, 70 F. I

A properly insulated storage container 79 is provided to receive theliquid carbon dioxide.

The said liquid carbon dioxide is to be stored in this container at aselected low temperature and corresponding low vapor pressure. We mayselect the temperature and pressure values referred to in connectionwith the disclosure oi! Fig. 1; i. e., a temperature of -5 F. and acorresponding vapor pressure of 280 pounds per square inch.

' The carbon dioxide stored in the container 19 is maintained at thedesired sub-atmospheric temperature by means of a refrigerating coil 88which is connected to a comparatively small reirigerating plant. It isto be understood that the capacity of this refrigerating plant need onlybe suflicient to take care of the absorption of heat which occursthrough the insulation 8| which surrounds the said tank.

The liquid carbon dioxide receiver 11 is connected by a pipe 82 to thelower portion of the storage container 19 and an expansion orpressurereducing valve 88 is locatedin this pipe line 82. The dome or top of thestorage container I8 is connected to a carbon dioxide vapor or gas line84 which is provided with an adjustable valve 85 and is illustrated asbelngconnected to the intake line 85 of the cylinder for the third stageof compression. It will be understood, however, that this line may beconnected with the intake line 58 for the cylinder of the second stageof compression, if desired. This gas or vapor line 84 is connected withthe intake for the third stage of compression if the selected storagepressure for the container 19 is higher than the second stage intakepressure. It the selected vapor pressure for the storage container v19is lower than the third stage intake pressure, the gas or vapor line 84then is connected to the gas intake line-58 for the cylinder 59 of thesecond stage of compression.

It will be appreciated that as the liquid carbon dioxide, which is at1000 pounds per square inch pressure and 70 F., passes through theexpansion or pressure reducing valve 88, the pressure of the liquidcarbon dioxide drops to the storage pressure of the container 18. Thisexpansion of the liquid carbon dioxide as it passes through the valve 88is accompanied by partial vaporization and the heat .of vaporizationresults in lowering the temperature of the liquid carbon dioxide beingdischarged into the container 18. The valve 85 in the carbon dioxide gasor vapor line 84 is adjusted to maintain a constant pressure in thestorage container 18. When this valve 85 is so adjusted, the quantityoi! gas returning to the compressor cylinder 88 or 59 will equal thequantity of carbon dioxide which vaporizes when passing through theexpansion valve 88 on ,its way from the receiver 11 to the storagecontainer 18.

There now have been disclosed two diflerent types of plants or equipmentwhich may be employed for 'making available the low temperature andcorresponding low pressure liquid carbon dioxide for handling by theremainder of the system. It has been seen that the low temperature, lowpressure liquid carbon dioxide may be point; The liquid carbon dioxideis to be charged into small cylinders, cartridges or drums by means ofthis installation so that the liquid carbon dioxide may be dispensed foruse. This plant includes a storage container assembly or large capacitywhich is designated in its entirety by the reference character 88. Thisstorage container assembly may consist of one or more individualcontainers or tanks with suitable insulating material arranged tocompletely surround the assembly. The construction of the individualtanks or containers and the enclosing insulating material will bedescribed in detail in connection with other figures.

This installation of Fig. 9 is adapted for use as a distributing plantwhich is located at a remote point with respect to the source of supplyof low temperature, low pressure liquid carbon dioxide;

1. e., either the plant disclosed in Fig. 1 or that disclosed in Fig. 2.The liquid carbon dioxide, therefore, must be transported to thestationary storage unit 88. As the liquid carbon dioxide is to be storedin this unit 88 at a selected, constant sub-atmospheric temperature andits corresponding vapor pressure, the liquid carbon dioxide should bedelivered to the container unit at the selected temperature andpressure. The transportation unit; therefore, should be of a characterwhich is capable of delivering the liquid carbon dioxide to the storagecontainer assembly 88 in approximately the desired pressure-temperaturecondition. Fig. l discloses a transportation unit 41 coupled with thedischarge of the installation receiving its quota of low pressure, lowtemperature liquid carbon dioxide. The installation disclosed in Fig. 9is shown with its storage container assembly 88 connected with atransport unit 41 for receiving low temperature, low pressure liquidcarbon dioxide from said transport unit.

To efl'ect transfer of the low temperature, low

pressure liquid carbon dioxide from the storage space of thetransportation unit to the container or containers of the assembly 86, asuitably driven centrifugal, rotary or reciprocating liquid pump 87 isemployed. The suction side of this pump is connected by a pipe line 88to the storage space of the transport unit 41. The discharge side of thepump 81 is suitably connected to the permanently installed pipe line 89which communicates with the individual container or containersbf thestorage assembly 86. If the type of pump 87 which is employed is notcapable of building up very much pressure difference between its suctionand discharge sides, when pumping a low viscosity liquid suchas carbondioxide, it is necessary to equalize the pressures in the storage spacesof the two units 41 and 86. This may be accomplished by means of atemporary connection or pipe line 90 which extends 2;; between the upperregions of the said storage spaces of the two containers. With thisarrangement, carbon dioxide gas will be permitted to pass from thestorage container or, containers '6 to the container of the transportunit 41 as liquid is transferredfrom the unit 41 to the container orcontainers 86 by means of the pump 81. This prevents a rise in pressurein the storage container or containers. At the end of the transferoperation, all of the liquid is in the storage container or containers66 and the container of the transport unit 41 is full of gas.

A typical storage container assembly 86 may have a normal workingpressure of approximately 300 pounds per square inch for which thecorresponding temperature of the carbon dioxide will be approximately F.Such a normal working pressure, of course, will be suitable for handlingliquid carbon dioxide at a temperature and a corresponding vaporpressure of the value specifically referred to in connection with theillustrated plants of Figs. 1 and 2. The individual containers of a lowpressure storage. assembly are designed for a maximum working pressurecorresponding to the pressure at which the system will be operated. Inthis manner, the savings in weight and cost of the equipment areobtained. It is necessary to prevent increase in the pressure of thecarbon dioxide stored in the containers of the assembly 86 and,therefore, it is necessary to remove any heat which penetrates theinsulation surrounding these containers. Inasmuch as the carbon dioxideis charged into the containers at the temperature-pressure conditionmaintained within the storage containers,

the means for removing heat from within the I containers need only havea capacity sufficient to take care of the heat losses through theinsulation. This desired result may be accomplished by equipping eachone of the individual containers with an evaporator coil 9|. Each coilis connected by the pipe 92 with the compressor 93 of a standardcommercial refrigerating unit which is permanently installed adjacentthe storage unit 86. An air cooled condenser coil 94 for thisrefrigerating unit is connected at one end to the compressor 93 by meansof the pipe 95. The remaining end of the coil 94 is connected to arefrigerant receiver 96. A pipe 91 extends from the receiver 96 to theevaporator coil 9| of the storage container 86. An expansion valve98,'of standard commercial construction, is arranged in the inlet lineleading to the evaporator coils 9| of the individual containers. Thisvalve and the remainder of the refrigerating mechanism will operate inthe usual way to effect refrigeration of the contents of the storagecontainers for the unit 86 and at a rate which, preferably, will removeheat from the interior of the unit 86 at least equal to the maximum rateof heat input. This refrigerating step may be accomplished at a very lowcost and will retain the liquidcarbon dioxide in the storage containersfor an indefinite period without any loss due to vaporization.

As a precautionary step, taken to prevent damage to the equipment orpersonal-injury in the event of failure of the refrigeratingu it, one ormore blow-off or pop-off valves 99 may be provided for each of theindividual storage containers. If one such pop-oil valve is employed foreach container, it may be set to start bleeding off the carbon dioxidegas at the maximum allowable working pressure of the storage container.If a plurality of safety valves are used, the additional valves maybeset to start bleeding off carbon dioxide gas at successively higherpressures with the result that each succeeding valve acts as a safetydevice for and will operate in the event of failure of the precedingvalve. The successively operating valves, therefore, are employed or.provided solely for the purpose of taking care of the situation whichwould arise as a result of failure of one or more of the series ofvalves. Of course, other well known forms of pressure relief devicesmight be used in place of pressure operated valves.

As suggested, the first safety valve may be set to operate at themaximum. working pressure of the storage container. As gas bleeds oilthrough the pressure operated valve, the contents of the storage tankare cooled by the refrigerating effect of the evaporation of carbondioxide liquid within the tank. This results in a drop in temperatureand consequently a drop in pressure within the container, thus causingthe blow-off valve to close. The quantity of liquid carbon dioxide whichwould bleed off through the pressure relief valve in the event offailure of the refrigeration system can be calculated since it would bethe ratio of the heat loss in B. t. u. per hour to the latent heat ofcarbon dioxide at the stored temperature. For example, at 0 F., thelatent heat is 120 B. t. u. per pound. A typical storage unit ofapproximately 8 tons liquid carbon dioxide capacity has a rate of heatpenetration through the insulation of approximately 1200 B. t. u. perhour. gas loss involved in maintaining the low pressure in the eventof-failure of the refrigeration unit would be a ratio of 1200:120, orapproximately pounds per hour. The loss in this typical case amounts toapproximately 1 in each 24 hours. This loss is less than the sublimationloss usually encountered in storing and handling solid carbon dioxide inthe form of dry ice.

It will be understood that the rate of heat penetration through theinsulation is a function of the temperature differences between the tankcontents and the exteriorsurface; of the total exterior area, and of thethickness and efficiency of the insulating material. It is possible,therefore, to limit the maximum rate of input by proper design of theinsulating jacket.

It has been determined that it is possible to charge the storagecontainers at temperatures and pressures lower than the maximumallowable workingpressure of the system. In this manner, the liquid canbe stored for an appreciable length of time without requiring therefrigeration machine to operate. The refrigeration Thus, the

unit may be caused to operate in response to a pressure controlmechanism which will function when a predetermined pressure, somewhatbelow the maximum allowable working pressure, is attained. As anillustration, liquid carbon dioxide may be charged into the typicalstorage container referred to above at a pressure of approximately 200pounds per square inch and at a temperature of -20 F., 'and stored forSeveral days without involving any cost for refrigeration, and withoutany gas loss through the operation of the pressure relief valve.

Customers of liquid carbon dioxide usually receive the same confined insmall cylinders, shells, 5 drums, or cartridges, which hold acomparatively few pounds of carbon dioxide. The installation disclosedin Fig. 9 includes equipment for charging such small cylinders, etc.

Charging plants now in commercial use employ compressors designed tocharge cylinders, or the like, with liquid carbon dioxide which ispumped from, a container holding liquid carbon dioxide at atmospherictemperatures and at pressures usually in excess of 1000 pounds persquare inch. This liquid is customarily expanded through an expansionvalve and enters the cylinder of the compressor where it is compressedto high pressures with an accompanying temperature rise which isconsiderable and then must be reliquefied by removal of the heat unitswhich were introduced to the fluid by the compression in the compressorcylinder. A considerable amount of power is needed to operate such acompressor. y In the installation shown in Fig. 9, a pumping unit I00 isemployed and, preferably, is operated by an electric motor IOI. Thedetails of this unit I00 are shown in Fig. 16 and will be morecompletely described in connection therewith. It will be stated at thistime, however, that the pumping unit I00 takes the form of areciprocating plunger type of compressor, which will function to receivethe liquid carbon dioxide from the storage container of the assembly 86and 4,5 deliver the carbon dioxide, still in a liquid state,

at an elevated pressure with no appreciable increase in the temperatureof the said liquid. This method of transferring liquid carbon dioxide isbelieved to be new with this invention. 50 For example, in a typicalinstallation, such as that disclosed in Fig. 9, the liquid pump I00 willreceive the liquid carbon dioxide at a pressure of 300 pounds per.square inch and at a temperature of 0 F. from the storage container 55orcontainers and raises the pressure to any desired pressure rangingfrom 800 pounds to 1500 pounds per square inch, depending upon the useto which the liquid is to be put. During this operation, the liquidremains at approximately 00 0 F.-

The suction side of the pumping unit I 00 is connected by the pipe I02with the lower portion or portions of the individual storage ccntainersof the assembly 86. The discharge side 05 of the unit I00 may beconnected by the pipe I03 with a receiver I04. The receiver may or maynot be insulated, as desired. A suitable number of charging heads orclamps I05 are connected to;

the receiver I04 by the pipe line I00.

70 When charging of cylinders, or the like, takes place, or when theapparatus is operating to charge cylinders, it is desirable tocontinuously operate the pumping unit I00. During such periods ofoperation, occasions may arise when no (5 cylinders are connected to thecharging heads or clamps I05. To prevent the building up of an excessivehydrostatic pressure in the receiver I04, 9. pressure relief or,blow-oflvalve of the type disclosed in detail in Fig. -17, is connected in thepipe line I03, as indicated at I01. This pres- 5 sure relief valve I0!is permanently connected to the top or tops of the individual storagecontainers by means of the pipe line I08.

To further explain the operation of this charging equipment, thereceiver I04 is constantly o supplied with liquid carbon dioxide bymeans of the unit I00 with the liquid carbon dioxide being at theelevated pressure required for the particular use and at the lowtemperature maintained in the storage containers. When a cyl- 15 inder,-or the like, is placed in communication with the receiver I04 by meansof one of the charging heads or clamps I05, the pressure in the receiverI04 drops 200 or 300 pounds immediately.

The pumping unit I00, however, quickly builds the go I pressure in thereceiver I04 back up again to the desired working pressure. This workingpressure preferably is approximately 1000 pounds per square inch. If thenext succeeding cylinder, or the like, is not ready for charging by thetime 25 the first cylinder is charged and disconnected,

and the pressure within the receiver I04 builds up to the predeterminedrelief pressure of the unit I00, shown in detail in Fig. 16, may be em-40 ployed to raise the pressure of the liquid from that of the storagecontainer or containers to that required in the charging clamps or headswithout raising the temperature. If the pumping unit I00 consisted of acompressor which handled the carbon dioxide in a gaseous state, it wouldbe impossible to effect charging of the cylinders, or the like, by meansof such a unit without input of heat. Pumping and boosting the pressureof the carbon dioxide while in a liquid state by the unit I00 avoids theinput of heat and permits the uni-t to be operated at a much lower rateof power consumption.

For example, at least one cylinder charging plant which has been inoperation for several years to charge cylinders by means of a compressorhandling the carbon dioxide in a gaseous state has been converted to acharging plant of the type described in connection with Fig. 9. Thischarging plant formerly required horse- 60 power to operate it when itcompressed the carbon dioxide in a gaseous state. This same plant, whenconverted, now operates on 15 horsepower, and it has been found to becapable of charging a considerably larger number of cylinders, or thelike, than was possible with the 60 horsepower equipment. This may beexplained by the fact that the weight of carbon dioxide gas entering agas compressor cylinder at 300 pounds per square inch suction pressureis 3 pounds per cubic foot-while the weight of liquid carbon dioxideentering the same cylinder at the same pressure is about 64 pounds percubic foot. Thus, the output from a given sized compressor cylinder isincreased twenty-fold when the unit handles liquid instead of gaseouscarbon dioxide. This can be achieved by omitting the expansion valve inthe suction line, thus maintaining the flooded suction condition in thecompressor intake. It also has been found to be desirable to increasethe compressor valve lift and clearance. In Fig. 10, there is discloseda modified form of refrigerating apparatus for a storage containerassembly which is designated by the reference character 86a. Thismodified refrigerating apparatus extracts heat from the liquid carbondioxide exteriorly of the said storage assembly.

A rotary liquid pump unit diagrammatically illustrated at I09 isconnected to the storage container or containers of the assembly 06a bya pipe line H0. The discharge of the pump unit I09 is connected by apipe III with a tube type of heat exchanger diagrammatically illustratedat H2. The refrigerated liquid carbon dioxide is returned to the storagespace or spaces of the containers constituting the unit 86a through thepipe line H3. The heat exchanger H2 is provided with conventionalheaders H4 and H5 which are interconnected by conventional tubes passingthrough the central portion of the exchanger. The header H4 is connectedby a pipe '6 to the intake of the compressor II! which forms a part of astandard commercial refrigerator unit. The discharge of the compressorII I is connected by the pipe III! with an air cooled condenser coilII9. The remaining end of this coil is connected. to a reeciver I20. Apipe I2I forms communication between the receiver I20 and the headerII5'of the heat interchanger. It is to be understood that this storagecontainer assembly 96a is to be provided with one or more safety valves99 in the same manner as that described in connection with the storageassembly 86 of Fig. 9. Suitable cylinder charging equipment of thecharacter disclosed in Fig. 9 also may be coupled with the storagecontainer assembly 86a in any suitable manner, for example, by means ofthe branch pipe lines I22 and I23. I

In connection with Fig. 9, there was disclosed one method and type ofapparatus which may be employed for effecting transfer of the lowtemperature, low pressure liquid carbon dioxide from. the container of atransport unit to the container or containers of a stationary storageunit. In Fig. 7, there is disclosed a further form of apparatus whichmay be employed. In this figure there is illustrated an insulatedstationary storage unit I24 which is intended to receive lowtemperature, low pressure liquid carbon dioxide from the transport unit41. The lower portions of the containers for both of the units 41 andI24 are placed in communication with each other by means of the pipeline I25 which is provided with a conventional form of quick detachablecoupling I26. The upper portions of the containers for the units 41 andI24 are connected by a pipe line I21 which has interposed therein a gascompressor I28 and a heat exchange unit I29 which includes a coil I30connected in series with the pipe line I21 and a steam heated water bathI3I.

When it is desired to effect transfer of the low temperature, lowpressure liquid carbon dioxide from the container of the unit 41 to thecontainer or containers of the a sembly I24, the pipe lines I25 and I 21are properly coupled with the unit 41, as illustrated. The gascompressor I28 is op-.

erated and functions to remove carbon dioxide 75 gas from the upperportion of the insulated container or containers of the assembly I24.This cold carbon dioxide gas handled by the compressor I28 is passedthrough the coil I30 which heats the said gas. This heated gas which, ofcourse, has been raised in pressure as well as in temperature, is forcedinto the container of the transport unit 41. This high pressure, hightemperature gas creates a pressure differential which causes the liquidcarbon dioxide to flow at a rapid rate through the pipe line I25 fromthe container of the transport unit M1 to the container or containers ofthe stationary storage assembly I24.

The description of the methods and apparatus of Figs. 7 and 9, whichrelate to transferring low temperature, low pressure liquid carbondioxide from the transport unit 41 to stationary storage containers,clearly point out that the container portion of the transport unit 41 ischarged with carbon dioxide gas during the withdrawal of the liquidcarbon dioxide. Thisgas remains in the transport container until a newcharge of low temperature, low pressure liquid carbon diox de is placedtherein, as is shown in Fig. 1. This gas pressure in the transportcontainer prevents the pressure of the liquid carbon dioxide fed to thecontainer when the latter is charged, for example, through the pipe 31in Fig. 1, from dropping below the pressure at which the liquid carbondioxide will flash and form snow, which pressure is approximately 75pounds per square inch.

In Figs. 2 and 9, there are disclosed stationary storage containerswhich are provided with cool ing coils 00 and 9I that are coupled withrefrigerating apparatus and which are located in the said containers ata level which will submerge the said coils in the liquid carbon dioxidebath contained within the containers. In Figs. 7 and 8, there isdisclosed a modified form of cooling coil for the stationary storagecontainers. The dome portion I32 of the storage container has positioned therein a cooling coil I33 which is connected by the branches I34 and I35 in circuit with refrigerating apparatus of the typeillustrated in Fig. 9. Fig. 7 discloses the use of an expansion valveI36 in the branch line I35.

This type of cooling coil has been found to effect appreciable economiesin maintaining the low temperature, low pressure liquid carbon dioxidestored in the container at its desired low values. As heat penetratestheinsulation surrounding the container, some liquid carbon dioxideevaporates and the gases or vapors rise therefrom into the interior ofthe dome I32. These carbon dioxide gases or vapors contact with thesurface of the cooling coil I33 and condense. The drops of condensationare returned by gravity to the liquid bath within the container. Itreadily will be appreciated that the total surface area of a coolingcoil of this character may be much less than the surface required in acoil of the character disclosed in either of the containers 8| and 86 ofFigs. 2 and 9.

In Figs. 3 to 5, inclusive, there is disclosed in detail a preferredform of transport unit which may be employed for conveying the lowtemperature, low pressure liquid carbon dioxide from a producing plant,or other source of supply, to a distribution plant. Figs. 3 and 4disclose the heavily insulated container unit as being mounted on atrailer I31 which maybe of any suitable design which is capable ofcarrying the load. The actual container I38 is secured to the chassis ofthe trailer I31 by means of proper tiedown bolts I39 which are suitablylocated and effectively connected to the chassis of the trailer and theside walls of the container I38. Suitable layers of cork insulatingmaterial I40 are arranged to surround and enclose the periphery of thecontainer I38. The forward closed end of the container also is coveredby properly fitted plies for layers of insulating material I4I. Asuitably shaped disc of insulating material I42 is fitted in place toproperly close off the rear end of the insulated space. Ground cork, orthe like, I43, may be employed for filling in the angles.

In Figs. 4 and 5, the container I38 is illustrated as being providedwith a suitable number of baffle plates I44 which are arranged to permituninterrupted communication between all portions of the interior of thecontainer 38 both above and below these bailles. For the purpose ofpermitting the attendant of the transport unit to ascertain the quantityof liquid carbon dioxide within the container I 38, a float I45 ismounted in the container on the float carrying arm I46. A mounting shaftI41 extends outwardly through the side wall of the container I38 and theinsulating plies I40 to receive at its outer end a pointer or indicatorarm I48 which is associated with a quadrant type of scale or gauge I49.The position of the pointer or indicator I48 with respect 60 thegraduations, not shown, on the gauge plate I49 will indicate theposition of the float I45 within the container.

A pressure gauge I58 may be properly associated with the forward end ofthe container I38 if desired. A pump 81 see Fig. 9, is connected to thelower portion of the container I38 by means of the pipe line 88. Aportion of the pipe line 90; employed for establishing communicationbetween the upper portion of the container I38 and the upper portion ofa stationary storage container, also is illustrated.

Figs. 3 and 4 disclose the dome portion I50 of the container I38 ashaving associated therewith a main pop-off or relief valve II and one ortwo additional safety relief valves I52.

Fig. 6 discloses the main pop-off or relief valve I5I in detail. Thispop-off valve includes a main casing body I53 which is provided with aninternally threaded part I54 which should be connected with a nipple, orthe like, extending into and communicating'with the interior of thecontainer I38. A suitable discharge port I55 for the valve body I53 isprovided by the nipple I56 which has formed at its inner end a valveseat I51 to receive the ball valve "I58. This ball valve is properlyconnected with a stem I 59 which in turn is connected with a diaphragmI60 secured to the flanged end I6I of the valve housing I53 by theflanged end I62 of a casing part I63. This casing part enclosed a heavyspring I64 employed to load the valve I58 so as' to maintain this valveseated until a rise in pressure within the container I38 functions toovercomethe load of the spring I84 and thereby unload and unseat thevalve I58. The pressure within the container I38 naturally acts upon theface of the diaphragm I60 which is exposed to the interior of the valvehousing I53.

For the purpose of varying the pressure at which the load of the springI64 will be overcome, a follower I65 bears against the outer end of thespring and is adjustably positioned by means of the set screw or boltI68. This bolt should be properly adjusted to provide the desiredpop-off pressure for the container I38 and then should be sealed by theelement I61 to prevent unauthorized tampering with the same.

In Figs. 11 and 12, there is disclosed in detail the construction of apreferred form of individual storage container. This container consistsof a tubular shell I which is welded at one end to a solid head In andis welded at its other end to a ring I12. ,The central opening of thering I12 is closed by a cover I13 secured in place by meansof a suitablenumber of stud bolts I14.

The evaporator coil 80 or 9I, see Figs. 2 and 9, has two branchesextending through suitable openings formed in the end cover I13.Suitable transversely extending coil supports I are mounted in the shellI10, as clearly illustrated in these two figures. of coupling membersI16 which are welded in apertures formed in the shell I10 and areemployed for establishing the desired connections between the interiorof the shell and the other units disclosed and described in connectionwith Figs. 2 or 9.

In Figs. l3, l4 and 15, there is disclosed a storage assembly whichincludes two container units of the character disclosed in Figs. 11 and12 and which are arranged side by side. These two container units aresuitably tied together and are surrounded by insulating material which,preferably, consists of cork'lagging units I11 covering the outer curvedsides of the two tanks and the cork boards I18 which span the spacesbetween the two containers. Regranulated cork I19 may be employed forfilling the spaces provided by the two containers and the cork boardsI18. The ends of the containers and the spaces filled by theregranulated cork I19 may be covered by cork slabs I80 and I8I. The slabI8I, of course, is provided with suitable openings to receive thebranches of the evaporator coils 9I, see Fig. 15.

In Fig. 16, there is disclosed in detail the pumping andpressureboosting unit designated by the reference character I00 in Fig.9. This unit consists of a conventional base casting I82 with a cylinderblock I83 properly mounted thereon. A reciprocating piston I85 ismounted in the cylinder I83 and is properly connected with a crank shaftI86 journaled in bearings carried by the base casting I82. The elementsso far described are of conventional design and may be found in anystandard commercially available air compressor.

The conventional cylinder head of the air compressor has been removedand the base I81 of a specially designed relatively small bore cylinderI88 substituted. This cylinder and base are clamped in position bysuitable bolts and nuts of the character formerly employed for securingthe. conventional cylinder head in place. The upper end of the cylinderblock I88 is flanged at I89 to have suitably secured thereto a cylinderhead I90 of special design.

A pumping plunger I9I reciprocates within the bore of the cylinder I88and is anchored at its lower end to the end wall I85'of the conventionalpiston I85 by means of the plate I92 and the securing devices I93.Packing material I94 is positioned within the cavity I95 formed in thecylinder I88 and is compressed by a packing gland I96. This packinggland may be adjusted by means of the bolts I91 and lock nuts I98 in themanner clearly illustrated.

"The cylinder head I90 is suitably bored to re-' ceive the valve cap I99to which the intake pipe I02, see Fig. 9, is connected. A valve seat 200is arranged at the inner end of the valve cap Fig. 12 discloses aplurality I99 and is adapted to have a valve 20I seated 7 stroke of theplunger I9I to admit liquid carbon dioxide to the bore of the cylinderI88. Upon the return or compression stroke of the plunger, the spring202 will seat the valve 20I.

The discharge pipe I03, see Fig. 9, is connected to the second valve cap203. The valve seat 204 is associated with the inner end of the valvecap 203 and is engaged by a valve 205 which is retained seated by thespring 86 during the suction 10 stroke of the plunger I 9I This valve205 will be moved oif of its seat during the compression stroke of theplunger.

The hydrostatic pressure relief valve I01, see Fig. 9, is disclosed indetail in Fig. 17. The coupling 201 is suitably connected in the pipeI03 and has connected thereto the casing section 208 by means of thenipple 209 mounted in one of the branches of the coupling 201. Thiscasing section 208 has a valve seat 2l0 mounted therein and designed tobe engaged by the ball valve 2| I.

A second valve casing part M2 is suitably threadedly connected to thefirst mentioned casing part 208 and functions to house a coil spring 2I3which engages the spring seat 2 at one end and the spring seat M5 at itsremaining end. The spring seat 2 bears against the ball valve 2| I toretain this valve seated until a predetermined hydrostatic pressure isbuilt up in the line I03. The spring 2| 3 will be compressed by movementof the ball valve 2 away from its seat as the result of the developmentof an excessive hydrostatic pressure.

The spring seat 2I5 is engaged by the threaded shank 2I6 of an adjustingrod 2I1 which is provided with a suitable manipulating handle 2I8 at itsouter end and passes through suitable packing 2I9 to prevent leakagearound the stem. Ad-. justment of the stem 2I1 inwardly or outwardly, byrotation of the stem, will eflect variations in the load applied to theball valve 2| I by the spring 2I3. By means of this adjustable stem,therefore, the hydrostatic pressure at which the ball valve ZII will beunseated may bevaried.

It is to be understood that the forms of this invention herewith shownand described are to be taken as preferred examples of the same, andthat various changes in the shape, size, and arra-ngement of parts maybe resorted to without departing from the spirit of the invention or thescope of the subjoined claims.

Having thus described the invention, what we claim is:

1. A method of handling a liquefied gas which must be maintained above75 pounds per square inch pressure to maintain it as a liquid comprisofcompression, cooling the gas after each stage of compression to-removethe heat absorbed by the gas, condensing the compressed gas to obtainliquid, lowering the temperature and pressure of the liquid to apredetermined selected sub-atmospheric temperature and its correspondingvapor pressure, which willbe above 75 pounds per square inch, anddelivering said low temperature, low pressure liquid without change intemperature and pressure to an insulated container charged with a fluidat a pressure which will prevent the pressure of'the incoming liquidfrom dropping below 75 pounds per square inch.

2. A method of handling a liquefied gas which must be maintained above75 pounds per square inch pressure to maintain it as a liquid comprisingpassing the gas through a plurality of stages of compression, coolingthe gas at each stage of 75 compression to remove the heat absorbed bythe ing passsing the gas through a plurality of stages gas, condensingthe compressed gas to obtain liquid, refrigerating the liquid to lowerthe temperature and pressure of the same to a predetermined selectedsub-atmospheric temperature and its corresponding vapor pressure, whichwill be above 5 75 pounds per square inch, and delivering said lowtemperature, low pressure liquid without change in temperature andpressure to an insulated container charged with a gas at a pressurewhich will prevent the pressure of the incoming liquid from 10 droppingbelow 75 pounds per square inch.

1 3. A method of storing a liquefied gas which 'must be maintained above75 pounds per square inch pressure to maintain it as a liquid whichcomprises the steps of charging an insulated .15,

pressure container with a liquefied gas at a subatmospheric temperatureand its corresponding vapor pressure, and maintaining the liquid in saidcontainer at a constant sub-atmospheric temperature and itscorresponding vapor pressure by 20 condensing the vapors in the vaporspace of the container and allowing the condensation to returnto'theliquid bath.

4. A method of storing and dispensing a liquefied gas which must bemaintained above '75 26 pounds per square inch pressure to maintain itas a liquid which comprises the steps of charging an insulated pressurecontainer of large capacitywith a liquefied gas at a pre-selectedsub-atmospheric temperature and its corresponding vapor pressure, 30maintaining the liquid in said container at approximately its chargingsub-atmospheric temperature and pressure by condensing the vapors withinthe container, withdrawing the liquid from said container whilemaintaining the normal 35 pressure in the container, and elevating thepressure of the withdrawn liquid while maintaining the temperature ofthe liquid at substantially the temperature prevailing in said pressurecontainer. 40

5. A method of handing a low temperature, low pressure liquefied gaswhich must be maintained above 75 pounds per square inch pressure tomaintain it as a liquid which comprises the steps of transferring from atransport container 45 to an insulated storage container of largecapacity a liquefied gas at a pre-selected sub-atmospheric temperatureand its corresponding vapor pressure, maintaining the liquid atapproximately the pre-selected sub-atmospheric temper- 5o ature whilestored in said insulated container, discharging the liquid from thestorage container for use, and maintaining all of the liquid in'theliquid phase and at approximately the same temperature during dischargewhile raising the pres- 55 sure to a considerably higher value.

6. A method of handling a low temperature, low pressure liquefied gaswhich must be maintained above 75 pounds per square inch pressure tomaintain it as a liquid which comprises the 60 steps of confining in aninsulated storage container of large capacity a liquefied gas at apreselected sub-atmospheric temperature and its corresponding vaporpressure, refrigerating the liquid while in the storage container at arate 05 sufllcient to remove heat units absorbed by the liquid,transferring the liquid from the storage container to a receiver andsimultaneously rais-' ing the pressure to'a value considerably higherthan the pressure of the stored liquid but without the addition ofappreciable heat, and charging small cylinders, or. the like, with theliquid at the high pressure and abnormally low temperature directly fromsaid receiver.

7. Apparatus for handling low temperature,

' 10 the liquid carbon dioxide from the storage container andcompressing it to a pressure appre- .ciably higher than the storagepressure while maintaining the temperature of the liquid substantiallyat the charging temperature, while being compressed. I

8. Apparatus for handling low temperature, low pressure liquid carbondioxide comprising an insulated transport container, a largecapacityinsulated storage container, pipe lines connecting go the upperand lower portions of said containers to efiect transfer of gaseous andliquid carbon dioxide respectively, a compressor in series with the pipeline connecting the upper portions of said containers, and means forheating the car- 85 bon dioxide gas fed from the compressor into thetransport container.

. 9. Apparatus for handling low temperature, low pressure liquid carbondioxide comprising a transport container, a large capacity insulated 30storage container, a rotary pump having a low pressure differentialbetween its suction and discharge sides connected with said containersfor transferring liquid carbon dioxide from the transport container tothe storage container with the 35 carbon dioxide at a pre-selectedsub-atmospheric temperature and its corresponding pressure, and meansfor equalizing the vapor pressure in the two containers during transferof the liquid.

10. In combination, a large capacity pressure 40 container, aninsulating jacket surrounding said container, said container beingadapted to be charged with liquid carbon dioxide at a pre-selectedsub-atmospheric temperature and its corresponding vapor pressure, areceiver, means for 45 conducting liquid carbon dioxide from the storagecontainer to the receiver, a reciprocating piston type compressor,having a flooded suction intake, connected in the conducting means forpumping liquid carbon dioxide from the storage container 50 to thereceiver and for simultaneously raising its pressure'to a valueappreciably above the storage pressure while allowing the temperature ofthe liquid to remain substantially-constant, means comprising a reliefvalve and a pipe line leading 55 to the container for preventing thebuilding up of an excessive hydrostatic pressure in said receiver, and aplurality of cylinder charging clamps connected to the receiver.

11. A method of handling a liquefied gas which m must be maintainedabove 75 pounds per square inch pressure to maintain it as a liquid,comprising converting the gas to a liquid and lowering the temperatureand pressure to a predetermined selected sub-atmospheric temperature andits corresponding vapor pressure, which will be above 75 pounds persquare inch, delivering said low temperature, low pressure liquid to aninsulated container without change in temperature and pressure, andcontrollably maintaining the 70 liquid at said low temperature andpressure while confined in said container by condensing the vapors inthe vapor space of the container.

12. A method of handling a liquefied gas which must be maintained above75 pounds per square 75 inch pressure to maintain it as a, l qu d,comprising converting the gas to a liquid andlowering the temperatureand pressure to a predetermined selected sub-atmospheric temperature andits corresponding vapor pressure which will be above 75 pounds persquare inch, charging said low 5 temperature, low pressure liquid intoan insulated transport container of large capacity having a gas chargewhich will maintain the pressure of the incoming liquid above 75 poundsper square inch, maintaining said liquid at substantially the 10selected low charging temperature and pressure -during transportation,transferring the liquid from the transport container to a stationarystorage container of several hundred pounds capacity without change intemperature and pressure and while charging the transport container withgas taken from the storage container to be used in refilling thetransport container, and controllably maintaining said liquid at saidlow temperature and pressure while in storage and while retaining boththe liquid and its vapor in said storage container.

13. A method of handling a liquefied gas which must'be maintained above75 pounds per square inch pressure to maintain it as a liquid,comprising converting the gas to a liquid and lowering the temperatureand pressure to a predetermined selected sub-atmospheric temperature andits corresponding vapor pressure, which will be above 75 pounds persquare inch, charging said low temperature, low pressure liquid into aninsulated transport container of large capacity having a gas chargewhich will maintain the pressure of the incoming liquid above '75 poundsper square inch, maintaining said liquid at substantially the selectedlow charging temperature and pressure during transportation,transferring the liquid from the transport container to an insulatedstorage container of large capacity without changing temperature andpressure while charging the 40 transport container with gas from thestorage container, controllably maintaining said liquid at said lowtemperature and. pressure while in storage, discharging the liquid fromthe storage container, and maintaining all of the liquid in the liquidphase and at the same temperature during discharge while raising thepressure to a considerably higher value.

14. A method of handling a liquefied gas which must be maintained above75 pounds per square inch pressure to maintain it as a liquid,comprising converting the gas to a liquid having a predeterminedselected sub-atmospheric temperature and its corresponding vaporpressure, which will exceed '75 pounds per square inch, by lowering thetemperature of the gas and converting the gas to a liquid, deliveringsaid low temperature, low pressure liquid to an insulated containerwithout change in temperature and pressure, and controllably maintainingthe liquid at said low temperature and pressure while confined in saidcontainer by condensing the vapors in the vapor space of the container.

15. A method of handling a liquefied gas which must be maintained above'75 pounds per square inch pressure to maintain it as a liquid,comprising converting the gas to a liquid having a predeterminedselected sub-atmospheric temperature and its corresponding vaporpressure, which will not exceed '75 pounds per square inch, by loweringthe temperature of the gas and converting the gas to a liquid,delivering said low tempertaure, low pressure liquid into an insulatedtransport container of large capacity having a gas charge which willmaintain the pressure of the incoming liquid above '75 pounds per squareinch, maintaining said liquid at substantially the selected low chargingtemperature and pressure during transportation, transferring the liquidfrom the transport container to a stationary storage container ofseveral hundred pounds capacity without change in temperature andpressure and inch pressure to maintain it as a liquid, comprisingconverting the gas to a liquid having a predetermined selectedsub-atmospheric temperature and its corresponding vapor pressure, whichwill exceed 75 pounds per square inch, by lowering the temperature ofthegas and converting the gas to a liquid, charging said low temperature.low pressure liquid into an insulated transport container of largecapacity having a gas charge which will maintain the pressure of theincoming liquid above 75 pounds per square inch. maintaining said liquidat substantially the selected low charging temperature and pressureduring transportation, transferring the liquid from the transportcontainer to an insulated storage container of large capacity withoutchanging temperature and pressure while charging the transport containerwith gas taken from the storage container, controllably maintaining saidliquid at said low temperature and pressure while in storage,discharging the liquid from the storage container, and maintaining allof the liquid in theliquid phase at the same temperature duringdischarge while raising the pressure to aconsiderably higher value.

17. A method of handling a liquefied gas which must be maintained above'75 pounds per square inch pressure to maintain it as a liquid,comprising charging said liquefied gas at a preselected sub-atmospherictemperature and its corresponding vapor pressure, which will be above'75 pounds per square inch, intoan insulated transport container oflarge capacity which has at the time of charging agas charge which willmaintain the pressure of the incoming liquefied gas at a pressure above'75 pounds per square inch, maintaining said liquid at substantially itscharging temperature and pressure during transportation, and effectingdischarge of said low temperature. low pressure liquefied gas at itspoint of, destination, said discharging operation resulting in leavingsaid transport container with a gas chargeto be used in the aforesaidmanner when the container is again recharged with liquefied gas.

. ERIC GEERTZ.

JESSE E. TAYLOR.

Patent. No. 2,180,251.

CERTIFICATE OF CORRECTION.

7 November 111, 1959. ERIC- GEERIZ, ET AL; v It is hereby certified thatthe above numbered patent was erroneously issued to "Cardox corporation"as assignee of the entire interest there in', whereas said p atentshould have been issued to the inventors, Eric Geertz and Jesse E.Taylor, .said eertz, assignor to Cardox Corporation, of Chicago,Illinois, a corporation of Illinois, as shown by the record ofassignments in this office; 'and that. the said Letters Patent should beread with this correction therein that the same may conformto the recordof the case in the Patent Office. Signed and sealed this 50th day ofJanuary, A. D. 1911;.

c Henry Vsn Arsdale, l) Acting Commissioner of Patents.

